Welcome to SYRCL's Ask a Scientist!
The Yuba River Watershed is full of curiosities. In “Ask a Scientist” we explore the questions you send us about observations you made while recreating around the watershed. We recently received a great question (and photos) from Diana Gardener.
Dear SYRCL Scientists,
I went for a hike today up Canyon Creek trail along the North Fork and saw something that alarmed me, and thought maybe you would have an idea of what’s going on.
Partway thru my hike I went down to the river for a dip, and found that the pool I was at had a massive fish die off in it. I saw at least 50 dead or dying fish from my perch. Once I hiked back up the cliff I could see many more littering the river bed in that area. I think they were rainbow trout. They don’t die after they spawn do they? As I hiked back up river I glanced down the cliff thru open spots, and saw a few more scattered fish, but not like in that one area. One dead one that I saw close up had an ulcer on it’s side. Any idea what’s happening? It has me worried!
My name is Tyler Goodearly, I’m SYRCL’s fish biologist. Thank you for sending the photos in, I always love getting pictures of fish! These look like Kokanee Salmon. Kokanee Salmon are landlocked versions of Sockeye salmon, which have been stocked in lakes in our watershed since 1969.
Kokanee follow similar life cycles as our native Chinook Salmon, but are solely found in freshwater. These fish hatch in a stream and then migrate to larger lakes, where they spend most of their adult life. When mature, they venture back upstream to spawn before perishing.
Although they are nonnative, Kokanee fulfill an ecosystem service that Chinook once served the North Yuba; their decomposing carcasses deposit nutrients higher up in the watershed to areas that need it. So, no need to panic seeing these dead fish! They’re just doing what nature intended them to.
For the Yuba,
Wondering about something you saw during your visit to the Yuba River Watershed? Submit your photos and thoughts to firstname.lastname@example.org to be featured in the next Ask a SYRCL Scientist column!